MS-900 Describe cloud concepts Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  Infrastructure as a Service (IaaS)

  Why it's wrong here

  With IaaS, the cloud provider supplies virtualized compute, storage, and networking, but the development team remains responsible for provisioning and patching the operating system, installing and configuring the web server and database middleware, and handling high availability and scaling. For a custom web application, this means significant operational overhead beyond writing code, whereas a platform layer would abstract those components. Thus, IaaS is not the most appropriate model here.

• ✓

  Platform as a Service (PaaS)

  Why this is correct

  PaaS offers a fully managed hosting environment—covering the operating system, language runtime, web server, and database—so the development team deploys only their application code and artifacts, while the provider handles patching, load balancing, and health monitoring. Azure App Service is a prime example: the team controls the code, connection strings, and some configuration, but not the underlying infrastructure, so they can focus on the app. This directly matches the requirement of deploying a custom web application without managing infrastructure.

• ✗

  Software as a Service (SaaS)

  Why it's wrong here

  SaaS delivers a complete, ready-to-use software application, such as Microsoft 365 or Salesforce, accessed over the internet with the vendor managing everything from infrastructure to application data and updates. In this scenario, the development team needs to deploy and run their own custom web application code, not subscribe to an existing product. As such, SaaS is unsuitable because it provides no mechanism for uploading arbitrary custom code and would require any customization to be done solely through vendor-defined configuration.

• ✗

  Function as a Service (FaaS)

  Why it's wrong here

  FaaS, such as Azure Functions, runs discrete pieces of stateless code in response to triggers like HTTP requests, queue messages, or timers, scaling each function independently. It is not designed to host a complete web application with a persistent web server, long-running sessions, or an integrated database layer, and an HTTP-triggered function would require additional services and custom code to replicate a full application stack. Because the team wants to deploy a complete custom web application, FaaS would introduce more complexity than PaaS and is therefore incorrect.

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